Articles
Effect of repeated low oxygen stress (RLOS) on superficial scald incidence on Packhams Triumph pears
Article number
1386_15
Pages
107 – 114
Language
English
Abstract
Repeated low oxygen stress (RLOS) can prevent superficial scald incidence on Packhams Triumph pears during long-term storage.
In certain seasons the alcohol build-up during the stress periods in the pear is higher than the prescribed maximum levels which can lead to off-tastes.
The aim of this study was to optimize the RLOS protocol to control superficial scald on optimum harvested Packhams Triumph over two consecutive growing seasons in South Africa. Packhams Triumph pears were subjected to repeated cycles of low O2 stress (0.5%) for 10 days after harvest and then 7 days for the following periods, followed by ultra-low O2 (0.9%) and 0.8% CO2 (RLOS+ULO) or controlled atmosphere storage of 1.5% O2 and 2.5% CO2 (RLOS+CA) at -0.5°C for 21 days.
In addition, fruit were stored under regular air (RA) as control.
Fruit were stored for 2, 4, 6, 8 and 10 months, followed by a simulated shipment and handling period (6 weeks in RA at -0.5°C) and 7 days at 20°C. A minimum of one stress and a maximum of 9 stress periods were applied over the storage period of 10 months.
One stress period was applied per month.
Ethanol concentration, superficial scald incidence and physicochemical properties were measured.
The RLOS+ULO treatment was effective to control superficial scald for 10 months with only one stress period at the beginning of storage.
When RLOS+CA is applied with only one stress period it is recommended to not store longer than 8 months.
The ethanol concentration build-up differed between seasons.
Application of monthly stress periods resulted in high ethanol concentrations in the RLOS+ULO treatment in the first season.
However, the fruit did not have any off-tastes after shelf life.
Both RLOS treatments resulted in fruit with good firmness and green background peel colour retention.
In certain seasons the alcohol build-up during the stress periods in the pear is higher than the prescribed maximum levels which can lead to off-tastes.
The aim of this study was to optimize the RLOS protocol to control superficial scald on optimum harvested Packhams Triumph over two consecutive growing seasons in South Africa. Packhams Triumph pears were subjected to repeated cycles of low O2 stress (0.5%) for 10 days after harvest and then 7 days for the following periods, followed by ultra-low O2 (0.9%) and 0.8% CO2 (RLOS+ULO) or controlled atmosphere storage of 1.5% O2 and 2.5% CO2 (RLOS+CA) at -0.5°C for 21 days.
In addition, fruit were stored under regular air (RA) as control.
Fruit were stored for 2, 4, 6, 8 and 10 months, followed by a simulated shipment and handling period (6 weeks in RA at -0.5°C) and 7 days at 20°C. A minimum of one stress and a maximum of 9 stress periods were applied over the storage period of 10 months.
One stress period was applied per month.
Ethanol concentration, superficial scald incidence and physicochemical properties were measured.
The RLOS+ULO treatment was effective to control superficial scald for 10 months with only one stress period at the beginning of storage.
When RLOS+CA is applied with only one stress period it is recommended to not store longer than 8 months.
The ethanol concentration build-up differed between seasons.
Application of monthly stress periods resulted in high ethanol concentrations in the RLOS+ULO treatment in the first season.
However, the fruit did not have any off-tastes after shelf life.
Both RLOS treatments resulted in fruit with good firmness and green background peel colour retention.
Authors
W.J. Botes, O.J. Caleb
Keywords
ultra-low oxygen stress, controlled atmosphere, ethanol, firmness
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